Certain cardiac morphologic findings are described in 16 necropsy patients having operative closure of an acquired ventricular septal defect (VSD) during acute myocardial infarction (AMI). The median interval from the onset of the AMI to death was 11 days, and from the onset of the AMI to operative closure of the VSD, 14 days. Eight patients died in the operating room or within 2 hours of operation. Death was attributed to unsuccessful VSD closure in 5 patients, to inadequate left ventricular cavity after resection of necrotic myocardium in 5 patients, and to inadequate viable left ventricular myocardium in 4 patients. Heart weights were increased in 14 patients (88%).